1. Field of the Invention
The invention relates to an exhaust system for a motor vehicle comprising a vehicle body and an internal combustion engine. The exhaust system has an exhaust which is intended for connection to the internal combustion engine and has at least one housing of a silencer and/or of a catalytic converter with a housing casing, having essentially a wall thickness of not more than 1 mm, and two housing ends and metallic pipes rigidly connected to the latter. The exhaust system furthermore has retaining means for holding the exhaust on the vehicle body.
The exhaust system is intended, for example, for a car but may also be used for another motor vehicle--for example a truck or bus. The internal combustion engine may consist of a gasoline or diesel engine.
2. Description of the Prior Art
European Patent Application Publication 0 807 749 and the corresponding U.S. Pat. No. 6,058,702 disclose exhaust systems which have pipes, a catalytic converter and at least one silencer, at least one of the pipes, the casing and the end walls of the housing of the or each silencer having a wall thickness of not more than 1 mm and preferably not more than 0.8 mm. Thanks to this light-weight construction, such an exhaust system has a very low weight. The exhaust systems have retaining means with holders which connect the housing of each silencer, in the vicinity of the housing ends, to the bottom of the vehicle. The holders have, for example, metallic retaining members fastened to the housing casing by spot welding or another welding method. Owing to the small material thickness of the housing casing, however, it is difficult to weld the retaining members in a stable manner to the housing casing without holes being formed in the latter. At least a part of the exhaust system and in particular at least one silencer are arranged in the tunnel of the vehicle bottom. Furthermore, there is generally only a small amount of space between the vehicle bottom and the surface on which the vehicle stands or drives. However, the holders fastened to the housing casing also occupy a certain height and reduce the height region available for the housing casing and hence the maximum possible cross-sectional dimensions of the silencer and its silencing effect.
German Patent Application Publications 30 26 730 and 31 37 746 disclose exhaust systems in which the housing of a silencer or pipes of the exhaust are suspended from the vehicle body by means of at least one rubber ring. If a force is exerted on an exhaust part held in this manner, the rubber rings initially offer only very little resistance to a deflection of the exhaust from its rest position. Only when the deflections of the exhaust parts reach limits of about 1 cm to 2 cm or even more does the resistance generated by the rubber rings increase abruptly. Retaining means comprising at least one rubber ring therefore have the disadvantage that the or each suspended part is virtually freely movable in particular upward and also in all approximately horizontal directions within certain ranges which are usually at least 1 cm or more. Exhaust parts suspended in this manner must therefore be large distances away from the vehicle body and--in the case of the arrangement in the tunnel of the vehicle bottom--in particular from the walls of the tunnel. Furthermore, exhaust parts suspended in this manner and the parts connected to them must have thick walls so that the exhaust is sufficiently strong.